> It's true that it's less dense, but "float" is a huge understatement. That is, it skitters, like water on a hot frying pan.

No, if you wrapped it in some impermeable coating so it couldn't react with water it would still float.

> But, I guess because it's less dense, it doesn't detonate as often as sodium or potassium do.

It doesn't "detonate as often" because it is less reactive than sodium and potassium because it is less likely to lose it's outer electron because that outer electron is closer to the nucleus.

That also means it is denser.